It is known to measure individual liquids in predetermined quantities or to mix two or more liquids to predetermined ratios for different purposes. To this end, there is normally used a measuring or mixing vessel to which one or more liquid delivery lines extend. With the intention of obtaining desired quantities of liquid, it is it is known to use more or less complicated control devices and control circuits which function to control said control devices and which in turn are influenced by the liquid present in the vessel. Hitherto, relatively qualified control equipment which includes communicating vessels, solenoid valves and/or complicated control systems have been required in order to achieve an adequately accurate result.